To calculate percentage, divide the number that is to be expressed as a percentage by the total or whole. The resulting number is then multiplied by 100 to obtain the percentage.
Percentage is a way to express fractions in an easily understood standardized format. The act of dividing a number by its possible whole is essentially that of converting a fraction into a decimal. When that decimal is multiplied by 100, the resulting number is the original fraction with a new denominator of 100. When every fraction is expressed with a common denominator, it allows for easier mental calculations and sets a baseline for quick comparisons.